Rail joint and bar



Oct. 25, 1932. G LANGFORD 1,883,982

' RAIL JOINT AND BAR Filed Nov. 7, 1950 4 Sheets-Sheet l Infra/afar. d cozya lagzyflwd QCL 25, 19326 LANGFORD 1,883,982

RAIL JOINT AND BAR Filed Nov. 7, 1930 4 Sheets-Sheet 5 5 Z961 i 1 39a (D 0 CD 0 (I) 0 MA A 1.22.4

CD 0 (I) 0 Oct. 25, 1932. s. LANGFORD RAIL JOINT AND BAR Filed Nov. 7, 1930 4 Sheets-Sheet 4 UNITED STATES PATENT; OFFICE,

GEGEGE LANGFi'lRD, OF JULIET ILLINOIS, ASSIGNOR TO MCKENNA PROCESS COMPANY OF ILLZNOIS, F JGLIET, ILLINOZS, A CORPORATION OF ILLINOIS BAEL JOINT AND BAR Application filed November The present invention has to do in general with bars used for bolting in pairs to rail ends in a track to make a joint, and has particular reference to novel features embodied in the fishing surfaces whereby the joint as a whole is maintained efficiently from the time the new bars are first applied to when they are worn out.

The main obj ect of the present invention is to modify the fishing surfaces of an ordinary type of bar, as to spacing and dimensions so that the bar will meet the structural conditions imposed upon it when in a track under vertical load. Another important object is to insure correct lateral movement of th bar to the rails when it is in a joint subject to wear. Still another object is to furnish a fishingcontact length corresponding to the bending moment length required in 29 the bar to function as a simple beam. An

other object is to produce as near as is possible a bar that will act with the rail ends while in a joint as an integral structure. Another object is to correct faults in long bars, unnecessary structurally but made so for certain purposes. till another object and the main one of this invention toward which the previously named objects are directed, is the construction of a rail joint by means of a bar with fishing contact surfaces so modified as compared with bars of known type, that when the bar is bolted to rail ends to make a oint, the bar will make tight contact at center under load and will act with the rail ends as an integral structure, maintainin the tight center and integral act-ion after wear of the fishing contacts begins under repeated loads. Further objects and advantages will become apparent from the following detail description.

In the drawings:

Figure l is a side view of a railroad track rail showing the vertical wave motion under load; I

Figure 2 is a side view of a rail joint under load, with the bars removed;

Figure 3 is a diagrammatic side view of a rail joint, unloaded;

Figure 4 is a diagrammatic side view of a rail joint, loaded;

Figure 5 is a diagrammatic side view of a joint under positive load;

Figure 6 is a diagrammatic side view ofa' joint under negative load;

Figure 7 is a diagrammatic side view of a long bar under positive load showing how the pressures and reactions apply;

Figure 8 is similar to Figure 7 but with the bar under negative load;

Figure 9 is a diagrammatic view of a short bar showing the rail ends and giving actual dimensions;

Figure 10 is a side view of a short bar laid over a long bar for purposes of comparison of the fishing surface lengths required for performance as a. simple beam,the end portions of the long bar being indicated by dotted lines;

Figure 11 is an inside view of a bar embodying the features of my invention showing the required fishing lengths;

Figure 12 is a section taken substantially on line 15 of Figure 11;

Figures 13 and 14 are perspective inside views of long six hole bars embodying three forms of my invention;

Figure 15 is an inside View of a long six hole bar in accordance with my invention;

Figure 16 is a section taken substantially on line 2121 of Figure 15;

Figure 17 is an inside view of a long bar in accordance with my invention with a short bar, also in accordance with my invention, ierposed upon the long bar; Figure 18 is an end view of the short bar of Figure 17.

In order to obtain a clear understanding of my invention it is necessary to consider the various actions and reactions, distribution of pressures, andother factors which affect the wear and performance of a rail joint.

It is well known to makers and users of rail j oints that only a very restricted portion of the length of the bar is subject to severe wear and strains, this restricted portion being at the center for a length of only a third or less of the length of the short bar and a considerably smaller proportion of the length of a long bar. As the central portion of the S ll loo

it is practically impossible to bend t bar wears on its fishing surfaces the end portions, which are reluctant to wear, resist drawing in of the bar at center by bolt tension as central wear occurs. Ordinarily, in the past bars were flexible enough laterally to beforced in at center by bolt tension, and as wear occurred on the fishing surfaces this wear was taken up to some extent by forcing the central portions of the bars to the rails. I-Iowever, the bars now in use, which are laterally stiffened with increase of section. and also by heat treatment, are strong enough latorally to resist inward bending at center, the bolts not being strong enough nor the tension applied by screwing up the nuts suflicient to bend the bars inward at center.

Although it is well known that the wear in a joint is restricted to a small central portion of the bar length and that as this restricted or central length becomes wornthe bars'must be bent in at center, nevertheless it has become very common practice for most of ourlarger rail 'oads using very heavy rail to also use bars much strengthened and stiffened, also heat treated, the result being that hem in to the rails laterally with. bolt tension so as to take up central wear. In addition the standard four hole 24 inch bar is in many instances being replaced by sir: hole bars 36 inches long and longer, particularly on heavy rails.

The main reason for using a long bar is to provide a three tie oint, with one tie directly under the center. The three ties are usually spaced somewhat closer to each other than are the rest of the ties in the body of the track, the purpose being to better distribute the load at the joint to the ballast by closer tie spacing at the joint. Inasmuch as the bars are fastened to the rail ends, and do not rest upon theties the use of the central tie and closer tie spacing does not strengthen the joint,merelyserving to distribute better the load through the track.

Due to the impracticability of designing a track structure of sufficient strength and stif ness to avoid deflection under the heavy loads imposed upon it, the ordinary track composed of steel rails resting upon cross ties embedded in ballast, will be given a vertical wave motion under the wheels of passing deflects downward; but for a distance 12 each side of 11, the deflection is upward and the rail is stressed by negative bending moments. \Vhen the wheel moves from the center of distance 11 to the center of distance 12, the conditions of verticaldeflection and bending conditionbreaks up the continuity of the wave motion.

In Figure 1, the length 11 is downwardly deflected by a distance 13, the rail assuming a curve under this deflection. However, in non-continuous track, the moving load P must pass over a. joint. Figure 2 is a side view of two rail ends 1 and 2 with the joint bars removed for purpose of description. As the load reaches the central position, the rail ends will deflect downward for the distance 13. This deflection is not accompanied by a gradual curve along distance 11 as'in Figure 1. Instead the rail ends merely bend sharply downward and have their top and bottom surfaces uncurved for the length 14 and 14 in each rail end, beyond which, curvature begins. The deflection 13 is also considerably greater than at 13 in Figure 1 and the reactions R and It become much greater near the center under pressure P. Vhen the joint bars are applied, they assume much of the bending moment, and there is a change from the conditions of Figure 2- to ward those of Figure 1; but to even closely approach the latter, the joint bars must be des gned so that the rail joint composed of rail ends and joint bars will compose an integral structure.

In the past it has been assumed that a joint made up of rail ends and well designed bars would result in integral action of bars and rail ends even under heavy moving loads. However, it has been found that because of the differences in curvature of bars and rail ends under load, tightness of the fishing contacts will not be uniform but restricted to limited areas, shifting as the load moves. An unworn joint not loaded may have uniformly tight fishing contact with the rail ends throughout the bar length but when under moving load, the forces which produce difference of curvature in the bars and rail ends are too great to be resisted by bolt tension, the only means available tohold the bars and rail ends in tight uniform fishing contact throughout the bar lengths. The bolts may yield but a slight amount, and yet this amount is sufficient to; loosen the fishing contact and permitsome independent action ofbars and'rail ends which with their overwhelming tendencies to assume difference of curvature under moving load, are quick to take advantage of lessened restrict on. This is assuming that the bolts are properly tight. If they are allowed to become loose, the independent action of rail ends, and bars increases. This independence of action between bars and rail ends is due to the diffilUO culty of so fitting the fishing contacts of the bars to therails at the central portion of the joint that there will not be any vertical movement between bars and rail ends at center when the joint is under load.

Railway engineers have decreed that while a tolerance of .002 or .003 of an inch vertical movement is permissible, this tolerance should be reduced to .001 of an inch to insure a first class oint. With this .001 of an inch tolerance the bars and rail ends should actalmost'as an integral structure. However, although bars and rail ends might be thus fitted when new, such a fit is most difiicult to maintain in ajoint when wear begins. The greater the vertical movement the great er the independent action of bars and rail ends.

Figure 3 is a diagraminatical side view of a long bar 15, and two rail ends 1 and 2, the line 1617 representing the head fishing surface of the bar and l8-1 the fiange fishing surface. Corresponding rail fishing surfaces are 2021 for the head fishing and"222-3 for the flange fishing. Figure 3, represents an unworn rail joint not under load.

Figure l is a View similar to Figure 3 bu with load applied near the center as indicated by arrow P. It his been shown by actual test, that when under positive load, the rail ends have very little curvature atthe center 24 and considerable curvature toward the ends, 25, the bars in turn having most of their curvature at the central portion and very little at the end portions. This means that wh n under positive load the fishing surfaces of rail ends and bar are in tightened contact at the center portion. 24 of the head fishing and at the end portions 26 of the flange fishings, also being in least contact at 27 of the flange fishings and 28 of the head fishings.

In a rail joint the bars will take all of the bending moment at the ends of the rails, but the rails will take all. of the bending moment at the ends of the bars, the intermediate bending moments being divided between rails and bars. In a joint under load the curvature of the rail ends increases from the center of the joint outward in either direction, while the curvature of the bars increases from the ends of the bars inward, so that under positive load thefishing surfaces of bars and rails become loose at some portions and tight at others, as shown in Figure l. This condition is more simply illustrated in Figure 5, where the joint is shown under positive load P. This load, because of the previously described variations of curvatures between bars and rail ends, has a limited length of contact 29, which represents the head fishing contact,the pressure on the rail head being transmitted through the under side to the bar head, this pressure being resisted by the reaction lengths 26 on the flange fishing surfaces where there is close contact. Figure 6 is illustrative of the negative load which results when the positive load P is away from the rail joint. The pressure is then appliedover the length 29 of the flange fishing of tr e bar, and the reactionsv are at 28 on the head fishing.

Due to the non-integral action between bars l rail ends and to the rev 1 al of conditions from posi 'e the, load passes over the o t, the locat ons ofapplied power and the reactions are con rntly shifting. in Figure 'l, which is diagraminatical side view of a long six hole bar under positive load P, due to difference of curvature between bar and rail ends, the load is concentrated as pressure for a short distance at each rail end little way from each rail end, as represented by lengths 29, which in the bar cov a length of FL. The reactions to these applied pressures are carried on very short ion the EL, whose central [poi t or resultant eaction, int mediate center and represented R w th the addition 7 D it reactions on the lengths RL. These concentrations of applied pressure and reactions are 'icted these v-ci limited lengths due, as previously explaii difference in curvature be .vcen the rail ends, these measurements var; iwhat in various types and sections f Figure 8 is the reverse of Figure 7, the first named showing the positive bendin niomt as applied, and the second the be ing as occurs when the load is away from the joint.

The conditions under positive loa ing for a long six hole bar as shown in Fi ure four hole short bar show no dinerence in the distribution of applied pressure and onlv 1 1 slight (inferences in the reaction distributo g-a" bars.

tions, except that in the long bar slight seconda y reactions are carried nearer the ends.

However, these secondary reactions h vve no noticeably marked effects, and for practical purposes the short bar fulfills the conditions of the long bar as regards lengths of the pressure and reaction surfaces.

It has been found in ordinary bars that the reaction lengths in a 24.111011 bar are restricted to a certain range this range being three inches or more dependin upon various conditions. This length appliesto bars of uniform fishing height and uniform widths of head and foot fishing surfaces throughout the bar length, these fishing surfaces being continuous from end to end. It must be remembered that in speaking of pressure. and reaction fishing surfaces, this refers to tigh ness of bar and rail fishing contact. The contacts elsewhere may be maintained without actual separations as shown in the diagrams, these being intended to illustrate variations in tightness of contact or pressure upon the bar and rail fishing surfaces i ri fishing surface. In Figure 11, ML represents the overall fishing contact length, which is the length required for bending moment. BL is the total bar length. HFL is the length of head fishing contact which takes the direct pressure under positive load, and F F L the length of flange fishing contact which takes the direct pressure under negative load. As the surfaces of HF L and F FL bear the brunt of pressure under load and have the greatest wear, their widths of fishing contact and 36 are made maximum or greater than the head and fiange fishings HFL and FFL, each side of the bars central portion, the width of which for the head is shown at 3?, and for the flange at 38. As HFL and FFL carry only the reactions away from center and not thetloadat center, wear on the reaction surfaces does not impair the tightness at center, therefore less width of fishing surface is required, and I make them of less width so that they may wear in amount as compared with the central fishings HFL and FF L to move inwardly under bolt tension at substantially the same rate or faster than the central fishings. In this way I avoid uneven take-up of the bar and the necessity of bending the bars in laterally at center as wear progresses. The end portions of the bar do a not require fishing contact, for the reason that they do not contribute to the bending moment which is provided for in the length ML. '1 he bar end fishings and 40 would therefore have no contact with the rail fishings, and the area of fishing contact at each end would be zero. In a track the central wear of top fishing surface under positive load is generally more severe than the central wear of bottom fishing under negative load, and so my invention is particularly directed to the proper design of fishing for the top surface of the bar. 7

In Figure 11 HFL may be defined as the head pressure length and FFL the fian e pressure length, these lengths being limited, as previously described, to five to seven inches for the head fishing and possibly a little more for the flange fishing, the respective widths of head and flange fishing being greater than in the intermediate and end portions of the bar. The moment length ML, representing the overall fishing contact, would likewise be limited to a length of from fourteen to twenty inches, having at least three inches or more fishing contact at each end. The width of the fishing surfaces at the intermediate portions of the bar, each side of the restricted central portion, are made substantially less than at the central portion. The portions at each end outside of the moment length BIL of Figure 11 will be referred to as end portions. These end portions will ordinarily have no fishing contact with the rails, although in special. cases they may have slight or partial contact for reasons to be explained. The symbols HFL, HFL', FFL, FFLQHFL and F F L and ML previously defined and limited as to lengths will be hereafter used in the figures and specifications, these symbols representing the lengths offishing surfaces as applying to ML equals bending moment length or overallfishing contact length. i

Referring to Figure 11 it maybe seen that the end portions are of considerable length. If entirely out of contactwith the rails, they are apt to result in a rattly or noisy track, and they may therefore be given very slight fishing contact with the rails so as to hold them in place, this, slight contact being too reduced to retard movement of the bars in at center as Wear occurs. This is shown in Figure 13 which is an inside perspective view of a bar 41 similar to that of Figure 11, except that the bar ends have small widths of fishing contacts EH and EF, which are considerably less than the intermediate fishing widths TH and IF, the latter in turn being substantially less than the central fishing widths CH and CF. The symbols CH, IH, EH,CF, IF and EF will be used hereafter to designate head and flange fishing widths at the central, intermediate and end portions of the bar. I

In Figure 13, which illustrates a long six hole bar, the reductions of fishing widths from center to ends are accomplished in three steps. Applied to the head fishing, these steps are CH, IH and EH, CH'and 1H being included in the restricted lengths HFL and EFL. The same is true of thefiange fishing surface. These reductions or steps are preferablyaccomplished in dies under a power press, although they might be madeless accurately by the method known in the art as multiple rolling.

More gradual reduction might be simpler from a practical standpoint as in the bar 42 of Figure 14. Here the width CH is maintained for the lengths HFL, then decreases gradually each side for the lengths HF L, this reduction continuing to the bar ends, or terminating with no effective fishing contact outside of the length ML. In Figure 14, the flange fishing reduction curve is reversed from that shown on the head fishing: This is merely a variation. Either curve may he applied to either fishing surface, and there Ill) are other methods of end reduction which may be employed. I

Figure 15 is aninside view of a long six hole bar 15, such bar being shown in section in Figure 16 as a flat strap to facilitate do scription. As the bending moment length, ML required for positive loading may be decreased somewhat for negative loading,

length ML may be slightly less than ML.

The head fishing at the ends of an ordinary long bar being in tight contact under negative load, and the end flange iishings in tight contact under positive load, these tight reaction contacts being outside of the bending moment lengths ML and ML, are a hindrance as they encourage greater deflection of the bar at center. The flange fishing surface is therefore tapered from a fishing height 46 beyond ML to a lesser height l? at each end. The head fishing may be similarly tapered at the ends to accommodate the tight end reaction contacts. The various treatments of the end portions of a long bar may be applied to shorter bars down to the maximum length of twenty inches required for bending moment, the lengths of the end portions only being reduced and all other lengths and Widths expressed by the symbols retaining the same measurements in the short as in the long bar.

WVhile my invention is particularly directed to reduction of fishing surface contact outside of the central portion of a bar, it may be applied to bars of ordinary fishing type 'wherein the widths of head and foot fishing 1 MI, W me ,7 ist eerltralfishiifg length may- 7 head =andvML fortli flange: inasziriitlieshortsbar; and inibotl be reversed, HML being longer than ML, the lengths of HML and ML being within the range of twenty to fourteen inch length. I do not wish to be limited, however, to a bar, one or both of whose fishing surfaces do not provide for rail contact for the full length of its end portions outside of the bars required moment length. ()nly a part of each end portion may not provide for rail contact, this being the extreme end portion where there is least wear and therefore greatest resistance of movement of the bar as a whole to the rails. This applies to all lengths of bars greater than the required moment length.

In my Reissue Patent No. 17,561, for rail joint, issued January 14, 1930, as a reissue of my original Patent N o. 1,5b2, l issued November 17, 1925, I disclose a bar with fishing surfaces decreasing in width from the central portion to the ends so as to in'iprove the tendency of ordinary bars to wear and move faster to the rails at center than at the'ends when the bar is in service in a joint. In my two copending applications, Serial Nos. 349,56? and 350,734, for tight center bar and even wear bar, respectively, filed March 28, 1929, I apply the to ching of reduced end fishing surfaces more specific'ally so as to have the bars move to the rails as fast as or faster than the center.

My Patent No. 1,T57,77 l, for rail joint and bar, issued'May 6, 1930, discloses a short bar, shorter than the 2d inch standard. short length, this shortened fishing length dispensing with the extreme end resistance to wear and reluctance of the ends to move inward. My patent and applications above identified disclose more or less broadly the general. teaching of reduced end iishings, leaving the proper design, of'ca bar as to its fishing sunfacestenecificaliy: nndetsnniuedi in [l' sure and reaction lengths, the e bei irNuinerous 1 th ec ssi. 7 mice permissible :1

fleeon curv a ur ends unde as a" simp, 'ct ns also;

tion 6 een-tr'alifishin-g ifit, to; 3 a nearly "approaching syin'metrv with to" thevliori zontal "gravity" :a. supporting i ties and' ballast.

LUZ

tain integral action of bars and 1". ds a oint under load. Figures on pr mr reaction and moment lengths in 0rd.

are available and I believe myself to first to teach that the overall elfecti c ing contact length should be ma .e to a imate the moment length, and the.

center where pressure occurs and at of the moment arm where the r actions 11 der pressure occur, the lengths should correspond o and reaction lengths, and furthermore, l a these lengths should be of prescribed to carry the loads and to insure even latera movement of the bars to the rails.

The present invention is fundamental and applicable to any design of bar and may be broadly defined as:

A principle of fishing contact construction in a bar with four or more bolt holes I" bolting to rail ends of he. I :ecti-cci to tori a joint in heavy duty track the being of any type that has top and bottom nshing contact, with fishing surfaces specifically designed to receive and distribute pres are and reactions under positive and negative l ading when in a joint. Each fishing s of the bar length is considered composed. of central portion, and an intermediate ant end portion in each half of the length. The fishings of the central portion which bear the brunt of pressure are of maximum width and of length corresponcing to the length which takes the load. The fishing height of the intermediate portion may be the same or less than that of the central portion, but the fishing surfaces are reduced in width or area to accelerate wear in service so that they may move to the rails under bolt tension as fast or faster than the central fishings. The overall length of the central. plus the two intermediate portions is the contact required for moment length and the outer ends of the intermediate port sufficient length to'receive the unimportant may be treated variously.

lhey may have very slight fishing contact or none, or only one fishing urface may have contact. As far as is practic-r bar has its fishing surfaces specifically signed to pertorin the :runctions of a sins 4- l and to ple beam when in a joint under loac secure uniform lateral movement to as wear occurs, and the bar is drawn to rail ends by bolt tension, the result bein tight center and integral action of bars an; rail ends when in a joint under load.

As my invention applicable ar form of head contact, full head Contact, had ire-e, flange free or other type of bar having provision for top and bottom fishiiv contact with rail ends; also to crowned, incurved, outcurved or otherwise shaped bars of angle or Z beam tyne, it i not thought necessary to figure or describe its application to the many t pes and variations. t may be used in the reforming of worn bars as well as in the manufacture of new ones. The length of fishing surface will be considered as its length from end toend regardless of any short gaps that might be placed in it for particular purposes. hat I claim is:

i a joint including the rail ends, a bar initially having top and bottom fishing contact n ith the rail ends at the center portion and intermediate portions of the bar for lengths top and bo tom respectively sufficient bending moments when the joint is subjected to positive and negative train loads, one of the top and bot-tom members of he bar being of substantially uniform width thr ughout its length and hava fishi surface in greater Mir th of rail 'ng contact at its center portion than at "i ermediate portions, with no rail fishing at it Xtlfilfle end portions, and said member l g no outward lateral delieci at a. portions.

' 'ncluding the rail ends, a the reduction of fishing surface as eennsd being applied to the top fishing suiiace, the center portion of which is of a length no more than sun' icient to take the pressure under positive train loads.

. in a rail joint including bile rail ends, 1: in claim 1, the reduction of fishing 1 e as defined being applied to thebotsurface, the center portion of ich is oa length no more than sufiicient to take the pressure under negative train loads. I

in rail joint including the rail ends, bar in claim 1, the reduction of fishing surface as defined being applied to both the top and bottom f surfaces of the bar.

5. in a ra l oint rjCidCllnf; the rail ends, bar as in or im 1, said bar being reformed from originally rolled bar.

in a rai joint Yacluding the rail ends, a bar in claim 1, the one of the top and bottom fishing surfaces out of rail fishing contact at its extreme end portions initially coming into rail fishing contact at its extreme end portions when the joint is under one of positive and negative train loads.

5 in a rail joint including the rail ends, ot' substantially uniform cross-section tiall saving top and bottom wear takeup space and top and bottom fishing contact with the rail ends its center portion and intermediate port ons for lengths at top and bottom suflicient respectively for bendin. moments when the joint is subjected to nositl and negative train loads, the top and bottom members of the bar being of substantially equal length, and one of said members being of substantially uniform width throughout its length and having no rail fish ing contact or outward lateral deflection at its extreme end portions.

8. In a rail joint including the rail ends, a bar as in claim 7, there being no rail fishing contact at the extreme end portions of both the top and bottom members of the bar.

9. In a rail joint including the rail ends, a bar as in claim 7, there being no rail fishing contact at the extreme end portions of the bottom member of the bar only. 7

10. In a rail joint including the rail ends, a bar as in claim 7, the respective lengths of top and of bottom rail fishing contact for bending moments being not less than 18 inches.

ll. In a rail joint including the rail ends, a bar as in claim 7, said bar being reformed from an originally rolled bar.

12. In a rail joint including the rail ends, a bar as in claim '4', the one of the top and bottom fishing surfaces out of rail fishing contact at its extreme end portions initially coming into rail fishing contact at its extreme end portions when the joint is under one of positive and negative train loads.

13. A rail joint bar providing for top and bottom rail fishing contact at its center portion and intermediate portions, one of the top and bottom members of the bar being of substantially uniform Width throughout its length and having a fishing surface providing for greater Width of rail fishing contact at its center portion than at its intermediate portions, and for lengths of top and bottom rail fishing contact sufficient respectively for bending moments When in a joint under train loads, there-being no outward lateral deflection or provision for rail fishing-com tact fat xt he entreme end portions of the bar. rali oint bar as in claim 13, said bar being of "uniform; fishing heightthroughout its 'center' portion and intern iediate portiODS". 1 7

1'5. In ahrail joint including'the rail ends, a bar of substantiallyuniform cross-section having top and bottom fishing contact with th'e rail-end-sat it's'center portion and intermediate'p'ortions for lengths attop' and bot tom"suflicient"respectively for bending moments vvhen the joint is subjected to positive and negative train loac s,"one 'at least of the top-ai'1d bottom' nembers 1 of the bar having no outn 'a 'rd deflection of nor rail fishing contact at its end portions.

16; Ina rail joint including the rail ends, axbar of substantially uniform cross-section having top and bottom fishing Contact with the railends at its center portion and intermediate portions for lengths at top and bottom sufficient respectively for bending mo ments when the joint is subjected to positive andrneg-ative trainloads, said bar being of 

